Unified Feedback Beamforming Digital Predistorter

Abstract

A novel digital predistortion (DPD) architecture for amplitude- and phase- weighted beamforming (BF) transmitter is proposed. Based on the analysis of BF nonlinear radiation characteristics over-the-air, the proposed DPD with a simple unified feedback circuit can reduce nonlinear radiation in every direction. The performance of proposed DPD is evaluated through computer simulation assuming Chebyshev-weighed BF arrays. The results show that the proposed architecture can suppress nonlinear radiation to less than -45 dB in all direction, which is similar to the full DPD architecture that requires individual feedback circuit for each antenna element.